I like trying to see where things that are obvious to me aren't to my clients.

I was recently working on building a mobile app for a web service, and I suggested to my client that he could open the API and give out the documentation. He didn't understand why, so I said developers might build more apps on their platform, or make little things like widgets.

It blew his mind, but it seemed totally obvious to me, so obvious that I almost didn't suggest it.